全文获取类型
收费全文 | 256篇 |
免费 | 34篇 |
专业分类
林业 | 24篇 |
农学 | 10篇 |
基础科学 | 2篇 |
74篇 | |
综合类 | 17篇 |
农作物 | 10篇 |
水产渔业 | 32篇 |
畜牧兽医 | 86篇 |
园艺 | 7篇 |
植物保护 | 28篇 |
出版年
2024年 | 3篇 |
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 17篇 |
2016年 | 14篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 33篇 |
2012年 | 17篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 17篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1978年 | 1篇 |
1973年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1903年 | 2篇 |
排序方式: 共有290条查询结果,搜索用时 31 毫秒
31.
Lucia Zappalà Antonio Biondi Alberto Alma Ibrahim J. Al-Jboory Judit Arnò Ahmet Bayram Anaïs Chailleux Ashraf El-Arnaouty Dan Gerling Yamina Guenaoui Liora Shaltiel-Harpaz Gaetano Siscaro Menelaos Stavrinides Luciana Tavella Rosa Vercher Aznar Alberto Urbaneja Nicolas Desneux 《Journal of pest science》2013,86(4):635-647
The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided. 相似文献
32.
Mark K. Asplen Gianfranco Anfora Antonio Biondi Deuk-Soo Choi Dong Chu Kent M. Daane Patricia Gibert Andrew P. Gutierrez Kim A. Hoelmer William D. Hutchison Rufus Isaacs Zhi-Lin Jiang Zsolt Kárpáti Masahito T. Kimura Marta Pascual Christopher R. Philips Christophe Plantamp Luigi Ponti Gábor Vétek Heidrun Vogt Vaughn M. Walton Yi Yu Lucia Zappalà Nicolas Desneux 《Journal of pest science》2015,88(3):469-494
33.
Colaço André F. Molin José P. Rosell-Polo Joan R. Escolà Alexandre 《Precision Agriculture》2019,20(4):805-822
Precision Agriculture - Site-specific management strategies are usually dependant on the understanding of the underlying cause and effect relationships that occur at the within-field level. The... 相似文献
34.
35.
Luigi Pane Elisabetta Giacco Christian Corrà Giuliano Greco Gian Luigi Mariottini Franco Varisco Marco Faimali 《Journal of Soils and Sediments》2008,8(2):74-79
Background, Aim and Scope The toxicity of contaminated sediments should be evaluated considering the direct exposure of laboratory organisms to whole
sediments and the indirect exposure to elutriates or extracts (Tay et al. 1992, Byrne and Halloran 1999, Nendza 2002). The
alga Dunaliella tertiolecta is indicated for the use in toxicity bioassays because it is highly sensitive to several xenobiotics. Harpacticoid copepods
have been already used for toxicity testing and Tigriopus fulvus is a promising Mediterranean target-species in ecotoxicology (Todaro et al. 2001, Faraponova et al. 2003, Pane et al. 2005a).
In this study, the toxicity of sediments collected in harbour sites of the Northeastern Adriatic Sea was evaluated by growth
inhibition test with free living and alginate-immobilized Dunaliella tertiolecta and acute toxicity test with nauplii and adult Tigriopus fulvus with the aim of pointing out the importance to utilize model organisms from different trophic levels in sediment ecotoxicology.
Methodology Elutriates and whole sediments were tested on free living and immobilized (Pane et al. 1998) algal cells, and on laboratory
reared copepods. Free-living D. tertiolecta were exposed to diluted elutriates in a static, multi-well plate system. Naalginate immobilized D. tertiolecta were placed in polystyrene inserts fitted with polyester mesh bottoms and exposed to a thin layer (2 mm) of whole sediments
in multi-well plates (EPS 1992, Pane and Bertino 1999). Toxicity tests with copepods were carried out on Tigriopus fulvus nauplii (elutriates) and adults (whole sediments and elutriates). Same-aged nauplii useful for toxicity tests were obtained
by egg sac detaching and consequent hatching stimulation (Pane et al. 2006). Newborn nauplii (I–II stage) were exposed to
elutriates in multi-well plates provided with polystyrene inserts. Adult T. fulvus maintained in polystyrene inserts fitted with polyester mesh bottoms were placed in contact with a thin layer (2 mm) of whole
sediment placed on multi-well plate bottoms. All end-points were evaluated after 96 h.
Results In general, the effects increased with the increasing of elutriate concentration up to 50%; the stimulation or inhibition
of algal growth was statistically significant in comparison to the control. The inhibiting elutriates induced EC50 variations of algal growth ranging from 66.9% to 74.3%. The mortality of T. fulvus nauplii was always < 25% after treatment with 100% elutriates and < 10% after treatment with 50% dilution; no effect was
shown up with 25% dilution; therefore LC50 was not calculable. The effect of elutriates was negligible on adult copepods and LC50 values were never calculable; percent mortality always resulted in < 10% after treatment with whole sediments.
Discussion Both experimental systems gave substantially similar results after exposition to whole sediments and elutriates. During the
experiment with algal cells, the immobilization in Na-alginate and the employment of inserts which allowed the contact of
organisms with sediments and their easy counting were particularly useful. Likewise, the employment of inserts of adequate
mesh size in the tests with copepods allowed the contact of organisms with the sediment and made organism handling and counting
easy, as well as the evaluation of mortality. The methodology here described and the utilization of the proposed test-species
could have an importance also considering that the current trend in ecotoxicological research is towards finding the most
appropriate organism for specific areas of concern by using indigenous species (Mariani et al. 2006) and towards the major
significance of chronic and reproductive end-points.
Conclusions Based on the above results, it can be stated that the bioassay with Dunaliella tertiolecta could be a good estimation tool for the ecotoxicological assessment of marine sediments. The immobilization of algae in Na-alginate
was seen to be useful to evaluate the toxicity of whole sediments; the employment of polystyrene inserts allowed an improvement
of the procedures. T. fulvus nauplii and adults, as other harpacticoids such as Tigriopus japonicus (Yoon et al. 2006), satisfy the basic criteria for the employment of a standard species in marine bioassays. To date only
pelagic Acartia tonsa are utilized in the standardized procedure to evaluate the risk assessment of chemicals or wastewaters (ISO 1999). As, on
the contrary, the exposure of copepods to solid-phase contaminants it is not yet standardized, the employment of polystyrene
inserts improved the procedures for T. fulvus too. So, the rapidity and the possibility to solve practical problems could be the main attractive features of this technique
(Pane et al. 2005a) when applied to whole sediments.
Recommendations and Perspectives The methodology here developed being also applicable to long term and reproduction tests should be recommended because it
provides relevant information in comparison with other frequently applied, standardized biotests with crustaceans (ISO 1999).
The procedure has been shown to be easily applicable to selected marine organisms.
ESS-Submission Editor: Prof. Dr. Henner Hollert (henner.hollert@bio5.rwth-aachen.de) 相似文献
36.
Zaragozá MC López D P Sáiz M Poquet M Pérez J Puig-Parellada P Màrmol F Simonetti P Gardana C Lerat Y Burtin P Inisan C Rousseau I Besnard M Mitjavila MT 《Journal of agricultural and food chemistry》2008,56(17):7773-7780
The consumption of seaweeds has increased in recent years. However, their adverse and beneficial effects have scarcely been studied. Two extracts from the brown seaweed Fucus vesiculosus containing 28.8% polyphenols or 18% polyphenols plus 0.0012% fucoxanthin have been obtained and studied to determine their toxicity in mice and rats and also their antioxidant activity. Both extracts were shown to lack any relevant toxic effects in an acute toxicity test following a 4 week daily treatment in rats. The extracts exhibited antioxidant activity in noncellular systems and in activated RAW 264.7 macrophages, as well as in ex vivo assays in plasma and erythrocytes, after the 4 week treatment in rats. Our ex vivo results indicated that compounds from extract 2 may be more easily absorbed and that the antioxidants in their parent or metabolized form are more active. These findings support the view that the daily consumption of F. vesiculosus extract 2 (Healsea) would have potential benefits to humans. 相似文献
37.
Effects of heating and autoclaving on sorption and desorption of phosphorus in some forest soils 总被引:1,自引:1,他引:0
A number of biological and chemical processes may affect soil phosphorus availability when forest fires occur, partly as a
result of heating. We describe here a laboratory experiment to study the effects of soil heating on changes in sorption and
desorption of P. Autoclaving was also included as an additional treatment of moist heating under pressure. Five forest soils
(two Podzols, one Arenosol, one Luvisol and one Alisol) were heated to 60°C, 120°C and 250°C or autoclaved for 30 min. They
were repeatedly extracted with Bray I and analysed for inorganic and organic P fractions. The desorbed P data were fitted
to an asymptotic exponential equation to obtain the desorption rate and capacity parameters. Podzol and Arenosol soils showed
a quick P desorption after heating, while Luvisol and Alisol soils showed a slow desorption rate. The immediate increase in
available P that occurred after heating or autoclaving originated mostly from solubilisation of microbial metabolites and
soil organic components. Autoclaving decreased P sorption capacity in all soils, but the effects of heating on P sorption
differed among soils. Except for one of the soils, the low P-fixing soils (Podzol and Arenosol) showed a decrease in P sorption
when heated to high temperatures, whereas the high P-fixing soils (Luvisol and Alisol) showed little changes after heating.
Fire intensity and soil characteristics are important factors determining short-term and long-term soil P dynamics. 相似文献
38.
M Amills D Villalba M Tor A Mercadé D Gallardo B Cabrera N Jiménez J L Noguera A Sànchez J Estany 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2008,125(4):228-233
A C3469T mutation at exon 3 of the pig leptin (Lep) gene has been genotyped in diverse pig breeds yielding controversial results with regard to its association with growth, fatness and carcass traits. A similar situation has been reported for a HpaII restriction fragment length polymorphism (RFLP) in the pig leptin receptor (Lepr) gene, where associations were found depending on the statistical model employed. The main objective of our work was to investigate if leptin plasma concentrations differ in pigs with different C3469T and Lepr HpaII RFLP genotypes. With this aim, we have measured plasma leptin levels at 160 days in 68 Landrace pigs with different Lep C3469T and Lepr HpaII RFLP genotypes. Neither Lep (TT: 11.68 ng/ml, TC: 10.71 ng/ml) nor Lepr (AA: 12.6 ng/ml, AB: 10.93 ng/ml, BB: 11.74 ng/ml) genotypes influenced significantly plasma Lep concentration. Moreover, we did not find any association between Lep and Lepr genotypes and phenotypic variation at growth and fatness traits in a commercial population of 320 Landrace pigs. 相似文献
39.
O Ramirez A Tomàs J Casellas M Blanch JL Noguera M Amills 《Reproduction in domestic animals》2008,43(5):542-546
The vascular cell adhesion molecule 1 (VCAM1) has a strong influence on embryonic development and on the formation of the umbilical cord and placenta. These developmental processes are crucial to ensure the success of pregnancy. In this work, we have identified two T306A and C558T single nucleotide polymorphisms (SNP) at exons 2 and 3 of the pig VCAM1 locus, respectively. The T306A substitution involves a non conservative Asn to Lys replacement at amino acid position 102, whereas the C558T polymorphism is synonymous. An in silico prediction of the consequences of the Asn102→Lys102 mutation with the PolyPhen software revealed that it is not deleterious. The T306A SNP segregated in the Iberian, Piétrain, Duroc, Large White and Landrace breeds as well as in European wild boars. The C558T SNP also segregated and most of commercial standard breeds. The genotyping of the C558T SNP in an Iberian × Meishan intercross allowed to find a suggestive association (Bonferroni threshold, p < 0.004) between C558T genotype and time the newborn piglet needs to reach the udder (p = 0.013) as well as a significant one with time to make the first ingestion of colostrum (p = 0.003). The biological basis of these associations remains unclear and they should be interpreted with caution. 相似文献
40.
Fractals and search paths in mammals 总被引:6,自引:0,他引:6
The fractal index by Katz and George (1985) for thecharacterization of planar curves is applied to wolf search pathsrecorded by radio-telemetry. All the sets of paths studied showspatial patterns whose complexity is between a straight line anda true random walk. Females fractal dimensions show significantchanges throughout the year, depending on the state of their lifecycle (normal, breeding and wandering). There are alsodifferences between males and females, but not between adults andnon-adults. The results are discussed with regard to wolffood-search strategies. 相似文献